Can you verify image if loaded on webpage?
Yes! You can verify but you cannot say that images are half loaded. To verify if image is correct then there would be some other method but code will tell you just that images are loaded on page or not.
You can send http request to that source using GET method and check the status code as 200. if that the case then your image downloaded properly and image is there.
Please drop your comments if you think if I am missing anything.